The bioassay-oriented isolation of strongylophorine-2, -3, and -8 (66–68) (Figure 6) from the MeOH extract obtained from the sponge Petrosia (Strongylophora) strongylata enabled their identification as inhibitors of the HIF-1-dependent luciferase expression in U251-HRE glioblastoma cells without interference with luciferase expression in U251-pGL3 control cells [280]. This evidence concerns the gene HIF1A and glioblastoma.